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java.lang.Objectorg.apache.commons.collections4.BagUtils
public class BagUtils
Provides utility methods and decorators for Bag
and SortedBag
instances.
Field Summary | |
---|---|
static Bag<Object> |
EMPTY_BAG
An empty unmodifiable bag. |
static Bag<Object> |
EMPTY_SORTED_BAG
An empty unmodifiable sorted bag. |
Method Summary | ||
---|---|---|
static
|
compliantBag(Bag<E> bag)
Returns a bag that complies to the Collection contract, backed by the given bag. |
|
static
|
emptyBag()
Get an empty Bag . |
|
static
|
emptySortedBag()
Get an empty SortedBag . |
|
static
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predicatedBag(Bag<E> bag,
Predicate<? super E> predicate)
Returns a predicated (validating) bag backed by the given bag. |
|
static
|
predicatedSortedBag(SortedBag<E> bag,
Predicate<? super E> predicate)
Returns a predicated (validating) sorted bag backed by the given sorted bag. |
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static
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synchronizedBag(Bag<E> bag)
Returns a synchronized (thread-safe) bag backed by the given bag. |
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static
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synchronizedSortedBag(SortedBag<E> bag)
Returns a synchronized (thread-safe) sorted bag backed by the given sorted bag. |
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static
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transformingBag(Bag<E> bag,
Transformer<? super E,? extends E> transformer)
Returns a transformed bag backed by the given bag. |
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static
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transformingSortedBag(SortedBag<E> bag,
Transformer<? super E,? extends E> transformer)
Returns a transformed sorted bag backed by the given bag. |
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static
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unmodifiableBag(Bag<E> bag)
Returns an unmodifiable view of the given bag. |
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static
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unmodifiableSortedBag(SortedBag<E> bag)
Returns an unmodifiable view of the given sorted bag. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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public static final Bag<Object> EMPTY_BAG
public static final Bag<Object> EMPTY_SORTED_BAG
Method Detail |
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public static <E> Bag<E> synchronizedBag(Bag<E> bag)
It is imperative that the user manually synchronize on the returned bag when iterating over it:
Bag bag = BagUtils.synchronizedBag(new HashBag()); ... synchronized(bag) { Iterator i = bag.iterator(); // Must be in synchronized block while (i.hasNext()) foo(i.next()); } }Failure to follow this advice may result in non-deterministic behavior.
E
- the element typebag
- the bag to synchronize, must not be null
IllegalArgumentException
- if the Bag is nullpublic static <E> Bag<E> unmodifiableBag(Bag<E> bag)
UnsupportedOperationException
.
E
- the element typebag
- the bag whose unmodifiable view is to be returned, must not be null
IllegalArgumentException
- if the Bag is nullpublic static <E> Bag<E> predicatedBag(Bag<E> bag, Predicate<? super E> predicate)
Only objects that pass the test in the given predicate can be added to the bag. Trying to add an invalid object results in an IllegalArgumentException. It is important not to use the original bag after invoking this method, as it is a backdoor for adding invalid objects.
E
- the element typebag
- the bag to predicate, must not be nullpredicate
- the predicate for the bag, must not be null
IllegalArgumentException
- if the Bag or Predicate is nullpublic static <E> Bag<E> transformingBag(Bag<E> bag, Transformer<? super E,? extends E> transformer)
Each object is passed through the transformer as it is added to the Bag. It is important not to use the original bag after invoking this method, as it is a backdoor for adding untransformed objects.
Existing entries in the specified bag will not be transformed.
If you want that behaviour, see TransformedBag.transformedBag(Bag, Transformer)
.
E
- the element typebag
- the bag to predicate, must not be nulltransformer
- the transformer for the bag, must not be null
IllegalArgumentException
- if the Bag or Transformer is nullpublic static <E> Bag<E> compliantBag(Bag<E> bag)
E
- the element typebag
- the bag to decorate, must not be null
IllegalArgumentException
- if bag is nullpublic static <E> SortedBag<E> synchronizedSortedBag(SortedBag<E> bag)
It is imperative that the user manually synchronize on the returned bag when iterating over it:
SortedBag bag = BagUtils.synchronizedSortedBag(new TreeBag()); ... synchronized(bag) { Iterator i = bag.iterator(); // Must be in synchronized block while (i.hasNext()) foo(i.next()); } }Failure to follow this advice may result in non-deterministic behavior.
E
- the element typebag
- the bag to synchronize, must not be null
IllegalArgumentException
- if the SortedBag is nullpublic static <E> SortedBag<E> unmodifiableSortedBag(SortedBag<E> bag)
UnsupportedOperationException
.
E
- the element typebag
- the bag whose unmodifiable view is to be returned, must not be null
IllegalArgumentException
- if the SortedBag is nullpublic static <E> SortedBag<E> predicatedSortedBag(SortedBag<E> bag, Predicate<? super E> predicate)
Only objects that pass the test in the given predicate can be added to the bag. Trying to add an invalid object results in an IllegalArgumentException. It is important not to use the original bag after invoking this method, as it is a backdoor for adding invalid objects.
E
- the element typebag
- the sorted bag to predicate, must not be nullpredicate
- the predicate for the bag, must not be null
IllegalArgumentException
- if the SortedBag or Predicate is nullpublic static <E> SortedBag<E> transformingSortedBag(SortedBag<E> bag, Transformer<? super E,? extends E> transformer)
Each object is passed through the transformer as it is added to the Bag. It is important not to use the original bag after invoking this method, as it is a backdoor for adding untransformed objects.
Existing entries in the specified bag will not be transformed.
If you want that behaviour, see
TransformedSortedBag.transformedSortedBag(SortedBag, Transformer)
.
E
- the element typebag
- the bag to predicate, must not be nulltransformer
- the transformer for the bag, must not be null
IllegalArgumentException
- if the Bag or Transformer is nullpublic static <E> Bag<E> emptyBag()
Bag
.
E
- the element type
public static <E> SortedBag<E> emptySortedBag()
SortedBag
.
E
- the element type
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